when was the last tune up,what type of gas/diesel are you using? Sometimes just blowing the carbon out the exhaust clears it up,then again it just started I would think gas,have you checked the fuel filter make sure all the wires are connected

A little over a year ago was my last tune up and 87 gas is what I use. It started yesterday when I was going through New Mexico now I'm stuck in Arkansas. Head to North Carolina from California. This is the 3rd time I've made this trip at first I thought it was because my truck is loaded down but now I'm thinking its something else.

The following web addresses have the obd1 procedure and trouble codes for your vehicle. You might want to print these codes and keep a copy in your glove box. The data link connector is under the steering wheel. The two pin connectors {A&B) at the upper right corner need to be jumpered with a small paper clip, then the key turned on, and watch the "service engine soon" lamp as it will flash any stored codes.
http://www.troublecodes.net/GM/
http://www.troublecodes.net/gm/gm-92-95-ck-pickup/